Generator employing piezoelectric and resonating elements

ABSTRACT

Disclosed are various embodiments of systems, devices and methods for generating electricity, transforming voltages and generating motion using one or more piezoelectric elements operably coupled to one or more non-piezoelectric resonating elements. In one embodiment, a non-piezoelectric resonating element is configured to oscillate and dissipate mechanical energy into a piezoelectric element, which converts a portion of such mechanical energy into electricity and therefore acts as a generator. In another embodiment, a piezoelectric element is configured to drive one or more mechanical elements operably coupled to the one or more non-piezoelectric resonating elements, and therefore acts as a motor. In still another embodiment, a piezoelectric element is operably coupled to a non-piezoelectric resonating element to form an electrical transformer. The mechanical properties of the non-piezoelectric resonating elements are typically selected to permit relatively high permissible stress and strain in comparison to the corresponding piezoelectric elements to which coupled or attached.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a continuation-in-part application, which takes priority fromdivisional application Ser. No. 14/060,121, filed on Oct. 22, 2013,which takes priority from non-provisional application Ser. No.11/635,775, filed on Dec. 7, 2006.

FIELD OF THE INVENTION

The present invention relates to the field of generators, motors andtransformers employing piezoelectric elements.

BACKGROUND

Different forms of rotating generators and motors are known. Typicalrotating motors and generators employ electromagnetic methods to convertelectrical energy to mechanical energy, or vice-versa. The constructionof an electromagnetic motor or generator is generally complicated.Materials such as copper or iron are often employed in theirconstruction, rendering such rotating motors and generators difficult touse in application requiring small size owing to their weight and bulk.The susceptibility of electromagnetic motors and generators to theinfluence of magnetic fields also limits their use in many applications.

A particular problem occurs when efforts are made to miniaturizeelectromagnetic motors and generators. While it is possible to scaledown the size of the motors and generators to produce low-power units,electrical conversion efficiency is appreciably reduced and furthermorethe fabrication of miniaturized units may be extremely complex. Manypresently available commercial electrical motors and generators are notsuitable for use in low power applications.

Although piezoelectric generators and motors of small size are known,many such devices suffer from limitations inherent in the variousmaterials employed to form the piezoelectric elements thereof. Forexample, many piezoelectric materials have permissible strains less than0.1%, which rather severely limits the amount of mechanical motion orelectrical current that can be generated using piezoelectric elements.

What is needed is a piezoelectric motor, generator or transformer havinga simple structure, that is light-weight, has low power consumption,permits easy control of speed and direction, produces no or low magneticfield interference with other devices and systems, and that is capableof generating higher levels of electrical current or power, or ofincreased mechanical output.

Various patents containing subject matter relating directly orindirectly to the field of the present invention include, but are notlimited to, the following:

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U.S. Pat. No. 5,917,268 to Takagi for “Vibration Driven Motor,” Jun. 29,1999. U.S. Pat. No. 5,936,328 to Takano et al. for “Linear VibrationActuator Utilizing Combined Bending and Longitudinal Vibration Modes,”Aug. 10, 1999.

U.S. Pat. No. 5,962,954 to Leers et al. for “Piezo-ElectricTransformer,” Oct. 5, 1999.

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U.S. Pat. No. 6,013,970 to

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U.S. Pat. No. 6,911,107 to Kagawa et al. for “Piezoelectric film typeactuator, liquid discharge head, and method of manufacturing the same,”Jun. 28, 2005.

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U.S. Pat. No. 7,002,284 B2 to Ouchi et al. for “Thin-FilmMicromechanical Resonator, Thin-Film Micromechanical Resonator Gyro, andNavigation System and Automobile Using the Resonator Gyro,” Feb. 21,2006.

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U.S. Pat. No. 7,089,638 to Yi et al. for “Method for fabricating amicromachined piezoelectric microspeaker,” Aug. 15, 2006.

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The dates of the foregoing publications may correspond to any one ofpriority dates, filing dates, publication dates and issue dates. Listingof the above patents and patent applications in this background sectionis not, and shall not be construed as, an admission by the applicants ortheir counsel that one or more publications from the above listconstitutes prior art in respect of the applicant's various inventions.All printed publications and patents referenced herein are herebyincorporated by referenced herein, each in its respective entirety.

Upon having read and understood the Summary, Detailed Descriptions andClaims set forth below, those skilled in the art will appreciate that atleast some of the systems, devices, components and methods disclosed inthe printed publications listed herein may be modified advantageously inaccordance with the teachings of the various embodiments of the presentinvention.

SUMMARY

Disclosed herein are various embodiments of systems, devices, componentsand methods for piezoelectric generators, motors and transformers havingone or more resonating elements forming operational portions thereof.

In one embodiment of the present invention, there is provided apiezoelectric generator comprising a piezoelectric element capable ofgenerating electrical current in response to at least one of movement,deflection and stress being applied thereto by an external force, anon-piezoelectric resonating element operatively coupled to thepiezoelectric element and configured to provide the external forcethereto, and a moving element configured to cause at least one ofmechanical movement and mechanical resonance in the resonating element,wherein the moving element causes at least one of mechanical movementand mechanical resonance in the resonating element when the movingelement moves under a prescribed range of operating conditions, andelectrical current is generated by the piezoelectric element when theresonating element applies external force thereto.

In another embodiment of the present invention, there is provided apiezoelectric motor comprising a piezoelectric element capable ofdeflecting or moving in response to an electrical current being appliedthereto, a non-piezoelectric resonating element operatively coupled tothe piezoelectric element and configured to resonate mechanically inresponse to the piezoelectric element deflecting or moving, and a movingelement configured to move in response to the resonating elementresonating under a prescribed range of operating conditions, wherein themoving element moves when electrical current is provided to thepiezoelectric element and the resonating element resonates in responsethereto under the prescribed range of operating conditions.

In still another embodiment of the present invention, there is provideda method of generating electricity, comprising operably coupling apiezoelectric element to a non-piezoelectric resonating element, using amoving element to deflect the resonating element to a first position a,releasing the resonating element from the first position a andpermitting the resonating element to deflect to a second position b,permitting the resonating element to oscillate between the first andsecond positions a and b, transferring mechanical energy generated bythe oscillating resonating element to the piezoelectric element, andgenerating electricity in the piezoelectric element in response to themechanical energy being provided thereto.

In yet another embodiment of the present invention, there is provided amethod of generating electricity comprising providing a piezoelectricelement capable of generating electrical current in response to at leastone of movement, deflection and stress being applied to thepiezoelectric element by an external force, providing anon-piezoelectric resonating element operatively coupled to thepiezoelectric element and configured to provide the external forcethereto, providing a moving element configured to cause at least one ofmechanical movement and mechanical resonance in the resonating element,wherein the moving element causes at least one of mechanical movementand mechanical resonance in the resonating element when the movingelement moves under a prescribed range of operating conditions, andgenerating electrical current in the piezoelectric element when theresonating element applies external force thereto.

In yet a further embodiment of the present invention, there is provideda method of generating motion in a moving element comprising providing apiezoelectric element capable of deflecting or moving in response toelectrical current being provided thereto by an external source ofelectricity, providing a non-piezoelectric resonating elementoperatively coupled to the piezoelectric element and having a portionthereof configured to deflect mechanically in response to piezoelectricelement deflecting or moving, providing a moving element configured tomove in response to the resonating element deflecting, and generatingmotion in the moving element when the piezoelectric element haselectrical current provided thereto.

In addition to the foregoing embodiments of the present invention,review of the detailed description and accompanying drawings will showthat there are still other embodiments of the present invention.Accordingly, many combinations, permutations, variations andmodifications of the foregoing embodiments of the present invention notset forth explicitly herein will nevertheless fall within the scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Different aspects of the various embodiments of the present inventionwill become apparent from the following specification, drawings andclaims in which:

FIG. 1 shows one embodiment of piezoelectric generator 10 of the presentcomprising rotor or mechanically moving element 16 having teeth 20 a-20g disposed along the outer periphery thereof;

FIG. 2 shows another embodiment of piezoelectric generator 10 of thepresent invention comprising teeth 20 a through 20 c disposed on movingelement or rod 16.

FIG. 3 shows yet another embodiment of piezoelectric generator 10 of thepresent invention comprising piezoelectric element 12 sandwiched betweennon-piezoelectric resonating element or spring bar 14 and base 18;

FIG. 4 shows still another embodiment of generator 10 of the presentinvention comprising magnets 22 a and 22 b mounted on the periphery ofmoving element or rotor 16;

FIG. 5 shows yet another embodiment of generator 10 of the presentinvention comprising magnets 22 mounted on the outer periphery of movingelement or rotor 16 that sweep past corresponding magnets 30 mounted onthe inner periphery of stator 28;

FIGS. 6a and 6b show another embodiment of generator 10 of the presentinvention, where magnets 22 mounted on the outer periphery of movingelement or rotor 16 sweep past corresponding magnets 24 mounted on theouter periphery of resonating element or rotor 14;

FIG. 7 shows yet another embodiment of piezoelectric generator 10 of thepresent invention comprising jet or orifice 36 configured to provideexternal force f₁ in the form of a jet or stream of liquid, gas or steam34;

FIG. 8 shows still another embodiment of piezoelectric generator 10 ofthe present invention comprising jets or orifices 36 a and 36 bconfigured to provide external force f₁ in the form of a combustionproduct;

FIG. 9 shows one embodiment of a MEMS device according to one embodimentof the present invention;

FIGS. 10a through 10c show some embodiments of electricity generatingsystems of the present invention;

FIG. 11 shows one embodiment of a transformer the present invention, and

FIG. 12 shows one embodiment of a method of the present invention forgenerating electricity.

The drawings are not necessarily to scale. Like numbers refer to likeparts or steps throughout the drawings.

DETAILED DESCRIPTION

Set forth below are detailed descriptions of some preferred embodimentsof the systems, devices, components and methods of the presentinvention.

The amount of energy E a mechanical element can store that is formed ofa given material is given by the equation:E=Y·ε ² ·V  (eq. 1)

where:

-   -   Y is Young's modulus of a material;    -   ε is the strain the material undergoes in response to an        external stress or force being applied thereto, and    -   V is the volume of the material subjected to the external force        and under strain.

If the material subjected to stress is a piezoelectric material, energymay be converted from mechanical to electrical forms by thepiezoelectric material (or vice-versa). The amount of power which can beconverted continuously by a piezoelectric material is given by theequation:P=f·k·E  (eq. 2)

where:

-   -   P is the amount of power converted by the piezoelectric        material;    -   f is the frequency of the mechanical oscillations of the        external force applied to the piezoelectric material, and    -   k is the energy conversion coefficient.

When mechanical resonance is induced in a piezoelectric element, thefrequency at which the piezoelectric element resonates is limited by itslongest dimension and other factors. Accordingly, a piezoelectricelement having relatively large physical dimensions has limited abilityto convert power owing to the low frequency at which it operates.Conversely, a piezoelectric element having small physical dimensions buthigh resonating frequency typically undergoes very small displacements,which are difficult to couple effectively to other elements of agenerator, motor or transformer.

Permissible strain in a piezoelectric element is given by the equation:

$\begin{matrix}{ɛ = \frac{h\;\delta}{l^{2}}} & ( {{eq}.\mspace{14mu} 3} )\end{matrix}$where:

ε is the permissible strain of a material (usually less than 1%);

δ is the displacement of the distal end 15 of resonating element 14;

h is the thickness of resonating element 14, and

l is the length of resonating element 14.

In accordance with various embodiments of the present invention,therefore, piezoelectric machines such as generators, motors andtransformers are made smaller and rendered more efficient by coupling anon-piezoelectric resonating element to a piezoelectric transducer. Thenon-piezoelectric resonating element provides a mechanical force or loadto the piezoelectric transducer. In a preferred embodiment of thepresent invention, the non-piezoelectric resonating element is formed ofa material such as steel, bronze, metal, a metal alloy, a combination ofmetals, plastic, polymer, carbon fiber, KEVLAR™, or silicon, orcombinations, laminations or composites of the foregoing, where thenon-piezoelectric resonating element most preferably, although notnecessarily, has a relatively high Young's Modulus, and therefore hashigh permissible strain and a high Q-factor exceeding those of aconventional piezoelectric material. The non-piezoelectric resonatingelement of the present invention permits relatively large displacementsof conventional mechanical elements to be coupled effectively andefficiently to conventional piezoelectric elements characterized byrelatively small displacements. The foregoing principles are illustratedby referring to the Figures and the accompanying text set forth below.

FIG. 1 shows piezoelectric generator 10 comprising piezoelectric element12 attached to base 18 and proximal end 17 of non-piezoelectricresonating element 14. An externally-provided force f₁ turns rotor ormechanically moving element 16 having teeth 20 a, 20 b, 20 c, 20 d, 20e, 20 f and 20 g disposed along the outer periphery thereof. As movingelement 16 rotates, tooth 20 a deflects distal end 15 of resonatingelement 14 into first position a. As moving element 16 continues torotate, distal end 15 of resonating element 14 releases from tooth 20 a,and under the action of force f₂ imparted by element 14 deflects intosecond position b, and then oscillates while tooth 20 b advances in thedirection of resonating element 14. Meanwhile, distal end 15 oscillatesand dissipates mechanical energy generated by such oscillation throughproximal end 17 into piezoelectric element 12. A portion of themechanical energy transferred into piezoelectric element 12 fromresonating element 14 is converted into electrical energy bypiezoelectric element 12. Once tooth 20 b engages resonating element 14and deflects element 14 into first position a, the process repeats. Notethat more than one resonating element 14 may be disposed along theperiphery of moving element 16. Note further that an electrical circuitfor storing and/or transferring electrical energy output bypiezoelectric element 12 in response to stress introduced therein byresonating element 14 is not shown in FIG. 1, such circuits being wellknown to those skilled in the art.

The characteristics, materials and dimensions of non-piezoelectricresonating element 14 are most preferably selected to maximize theefficiency with which resonating element 14 transfers energy from movingelement 16 to piezoelectric element 12. For example, during thoseperiods of time when distal end 15 of resonating element 14 is freelyoscillating between adjacent teeth, the resonating frequency, length andwidth of resonating element 14, and the material(s) from whichresonating element 14 are formed, are most preferably selected so thatcontinued mechanical oscillation of resonating element 14 hassubstantially subsided or abated by the time the next tooth engages anddeflects distal end 15 of resonating element 14.

The principal resonant frequency and the stiffness of resonating element14 should be selected to permit the piezoelectric element to constitutethe main source of loss in the mechanical resonance of the system. Thenumber of resonating elements 14 may be greater than one and may behigher, lower, or equal to the number of teeth or deflecting elements 17in rotor or moving element 16. If multiple resonating elements 14 areemployed, such elements 14 need not have the same or equal resonantfrequencies. Indeed, certain advantages may obtain from having aplurality of resonating members having different resonant frequencies,depending on the particular application at hand.

Continuing to refer to FIG. 1, the displacement of the free or distalend 15 of resonating element 14 is proportional to the square of thelength of element 14 between its distal and proximal ends 15 and 17.Because resonating element 14 of the present invention is formed from anon-piezoelectric material, its length can be much shorter than that ofan otherwise similar resonating element formed from a piezoelectricmaterial. This shorter length translates into a higher resonatingfrequency for resonating element 14 than a piezoelectric material wouldbe capable of providing.

In addition to being able to operate at higher frequencies, thematerials from which resonating element 14 are most preferably formedhave relatively high Young's Modula, and therefore are capable of beingdeformed to a much greater extent than piezoelectric materials. Forexample, most piezoelectric materials have permissible strains thatpermit deformations on the order of 0.1%. Contrariwise, materials suchas steel, metal, metal alloys, metal combinations, brass, silicon, somemicro-machined micro-electrical mechanical systems (MEMS) semiconductormaterials, and the like have permissible strains permitting deformationson the order of 0.5% to 1%, which are nearly an order of magnitudegreater than those permitted by conventional piezoelectric materials.

One example of a preferred material from which to form resonatingelement 14 configured for use in a very small machine is silicon or asimilar material such as a material suitable for use in fabricating MEMSsemiconductor substrates, more about which I say below. Silicon has ahigher permissible stain than steel and is also nearly losslessmechanically, unlike steel, which converts relatively large amounts ofenergy into heat during oscillation. The use of silicon to formresonating element 14 permits the construction of very small but highlyefficient piezoelectric generators, motors and transformers, more aboutwhich I say below. MEMS batch fabrication techniques well known to thoseskilled in the art such as batch microfabrication processes,photolithography, wet and dry etching, oxidation, diffusion,low-pressure chemical vapor deposition (LPCVD), sputter deposition,plating, molding, substrate bonding, bulk silicon micromachining, andpolysilicon surface micromachining may be employed to form resonatingelement 14, as well as to form moving element 16, piezoelectric element12 and base 18 of the present invention. For example, very small beamsor springs may be attached to, fabricated on or in a silicon substrateto form resonating element 14, which is then operatively coupled topiezoelectric element 12 disposed thereon. In one MEMS embodiment of thepresent invention, one or more magnets, magnetized materials or magneticlaminates are mounted on, in or to distal end 17 of resonating element14 so as to cause resonating element 14 to move in the presence of amagnetic field.

Continuing to refer to FIG. 1, the frequency at which resonating element14 vibrates in response to being deflected and released by teeth 20 isgiven by the equation:f _(p) >>Qf _(t)  (eq. 4)where:

f_(p) is the resonant frequency of resonating element 14;

f_(t) is the frequency at teeth 20 hit the resonating 14, and

Q is the mechanical quality factor of resonating element 14.

Here, the “much greater” sign in equation 4 typically translates intofrequency f_(p) being 5 to 10 times greater than f_(t).

FIG. 2 shows another embodiment of piezoelectric generator 10 of thepresent invention, comprising piezoelectric element 12 attached to base18 and proximal end 17 of non-piezoelectric resonating element 14. Anexternally-provided force f₁ pushes teeth 20 a through 20 c of movingelement or rod 16 towards distal end 15 of non-piezoelectric resonatingelement 14. As shown in FIG. 2, resonating element 14 deflects intofirst position a under the action of force f₁. When tooth 20 a advancespast distal end 15 of resonating element 14, resonating element 14deflects into second position b under the action of force f₂. Whiletooth 20 b advances in the direction of resonating element 14, distalend 15 oscillates and dissipates mechanical energy generated by suchoscillation through proximal end 17 into piezoelectric element 12. Aportion of the mechanical energy transferred into piezoelectric element12 from resonating element 14 is converted into electrical energy bypiezoelectric element 12. Once tooth 20 b engages resonating element 14and deflects element 14 into first position a, the process repeats. Asin FIG. 1, note that an electrical circuit for storing and/ortransferring electrical energy output by piezoelectric element 12 inresponse to stress introduced therein by resonating element 14 is notshown in FIG. 2, such circuits being well known to those skilled in theart.

FIG. 3 shows yet another embodiment of piezoelectric generator 10 of thepresent invention, comprising piezoelectric element 12 sandwichedbetween non-piezoelectric resonating element or spring bar 14 and base18. One or more external forces f_(1a) and f_(1b) deflect one or more ofdistal ends 15 a and/or 15 b of resonating element or spring bar 14. Asshown in FIG. 3, resonating element 14 is deflected into first positiona by external forces f_(1a) and f_(1b), forces f_(1a) and f_(1b) arereleased, resonating element 14 deflects into second position b underthe action of forces f_(2a) and f_(2b) imparted by spring bar 14, andspring bar 14 oscillates and dissipates mechanical energy generated bythe oscillation into piezoelectric element 12. A portion of themechanical energy transferred into piezoelectric element 12 from springbar 14 is converted into electrical energy by piezoelectric element 12.When external force f produced by acceleration of the projectile fromthe barrel is applied to one or more distal ends 15 a and 15 b, inertiaprovided by spring bar 14 causes deflection of bar 14 into firstposition a. Thereafter, distal ends 15 a and 15 b undergo furtheroscillation. The embodiment of the present invention illustrated in FIG.3 may be adapted for use in armed projectiles, where generator 10 is afuse that oscillates and generates electricity upon being ejected fromthe barrel of a gun, cannon, artillery piece, tank or otherprojectile-shooting device. Such an embodiment of the present inventioneliminates the need for batteries in armed projectiles, which are knownto have limited shelf life.

FIG. 4 shows still another embodiment of generator 10 of the presentinvention, where magnets 22 a and 22 b mounted on the periphery ofmoving element or rotor 16 sweep past distal end 15 of resonatingelement 14 in response to an external force f₁ being provided to causerotation of rotor 16. Resonating element 14 has mounted on distal end 15thereof magnet 24. As magnet 22 a sweeps past magnet 24, resonatingelement 14 deflects into first position a, and then deflects into secondposition b under the action of force f₂ imparted by element 14 aftermagnet 22 a has moved past distal end 15. Resonating element 14oscillates and dissipates mechanical energy generated by the oscillationinto piezoelectric element 12. A portion of the mechanical energytransferred into piezoelectric element 12 from resonating beam orelement 14 is converted into electrical energy by piezoelectric element12. When magnet 22 b moves into position beneath magnet 24, resonatingelement 14 deflects into first position a, and the process repeats.

FIG. 5 shows yet another embodiment of generator 10 of the presentinvention, where magnets 22 mounted on the outer periphery of movingelement or rotor 16 sweep past corresponding magnets 30 mounted on theinner periphery of stator 28. External force f₁ causes rotation of rotor16. The interaction of moving magnets 22 with substantially stationarymagnets 30 causes stator 28 to oscillate in place between springs orresonating elements 14 a and 14 b, the proximal ends 17 a and 17 b ofwhich are operably mounted on piezoelectric elements 12 a and 12 b, andthe distal ends 15 a and 15 b of which are operably connected to stator28. As magnets 22 sweep past magnets 24, resonating elements 14 a and 14b deflect under the action of forces f_(2a) and f_(2b) provided byelements 14 a and 14 b after each magnet 22 causes a correspondingmagnet 30 to move. Resonating elements 14 a and 14 b oscillate anddissipate mechanical energy generated by such oscillation intopiezoelectric elements 12 a and 12 b. A portion of the mechanical energytransferred into piezoelectric elements 12 a and 12 b from resonatingsprings or elements 14 a and 14 b is converted into electrical energy bypiezoelectric elements 12 a and 12 b. When magnets 22 move further alongthe insider periphery of stator 28 into position beneath magnets 24,resonating elements 14 a and 14 b deflects once again, and the processrepeats.

Continuing to refer to FIG. 5, note that if the number of poles on rotor16 equals the number of poles on stator 28, the number of principal setsof movement or oscillation of resonating elements 14 a and 14 b willequal the number of poles. If, however, the number of poles on rotor 16does not equal the number of poles on stator 28, the number of principalsets of movement or oscillation of resonating elements 14 a and 14 bwill be higher than either the number of rotor poles or stator poles.For example, where the numbers of poles on the rotor and stator aredifferent by one, then the number of principal sets of movement ofresonating elements 14 a and 14 b will equal the number of rotor polestimes the number of stator poles. As a result, the individual principaloscillations induced in resonating elements 14 a and 14 b will be ofsmaller amplitude but greater frequency. This principle may be employedto increase the efficiency of various embodiments of piezoelectricgenerators, motors, and transformers of the present invention, and inparticular in small such devices.

FIGS. 6a and 6b show another embodiment of generator 10 of the presentinvention, where magnets 22 mounted on the outer periphery of movingelement or rotor 16 sweep past corresponding magnets 24 mounted on theouter periphery of resonating element or rotor 14. External force f₁causes rotation of rotor 16. The interaction of moving magnets 22 withrotationally constrained magnets 24 causes resonating element or rotor14 to oscillate under the action of force f₂ imparted by rotor 14 in adirection perpendicular to the direction of rotation of rotor 16. Notshown in FIG. 6a is a spring that biases rotor 14 against rotor 16, andthat permits rotor 14 to oscillate back and forth along the axis ofrotation of rotor 16. Also not shown in FIG. 6a is the operable couplingof such a spring to a piezoelectric element to permit mechanical energygenerated by the oscillation of rotor 14 to be dissipated intopiezoelectric element 12. FIG. 6b shows such operable coupling ofelements 12, 14 and 16. A portion of the mechanical energy transferredinto piezoelectric element 12 from resonating element 14 and itscorresponding spring is converted into electrical energy bypiezoelectric element 12. When magnets 22 move further along theperiphery of rotor 14 into position adjacent magnets 24, resonatingelement 14 deflects once again, and the process repeats.

FIG. 7 shows yet another embodiment of piezoelectric generator 10 of thepresent invention, comprising piezoelectric element 12 attached to base18 and proximal end 17 of non-piezoelectric resonating element 14, andjet or orifice 36 which provides external force f₁ in the form of a jetor stream of liquid, gas or steam 34. Note that as employed herein, theterm “gas” includes within its scope air. Externally-provided jet orstream of gas, liquid or steam (providing force f₁) acts on distal end15 of non-piezoelectric resonating element 14 through jet or orifice 36for a first predetermined period of time and at a pressure sufficient,and at a distance sufficiently close, to cause the desired amount ofdeflection of distal end 15 of resonating element 14, after which firstpredetermined period of time the supply of gas, liquid or steam isterminated until the next cycle of providing force f₁ begins. As shownin FIG. 7, resonating element 14 deflects into first position a underthe action of force f₁, force f₁ is released, resonating element 14deflects into second position b under the action of force f₂, and thenoscillates and provides mechanical energy to piezoelectric element 12through proximal end 17. A portion of the mechanical energy transferredinto piezoelectric element 12 from resonating element 14 is convertedinto electrical energy by piezoelectric element 12. After a secondpredetermined period of time has passed since the termination ofproviding external force f₁, force f₁ is provided again to deflectelement 14 into first position a, and the process repeats.

FIG. 8 shows still another embodiment of piezoelectric generator 10 ofthe present invention, comprising piezoelectric element 12 attached tobase 18 and proximal end 17 of non-piezoelectric resonating element 14,and jets or orifices 36 a and 36 b configured to provide external forcef₁ in the form of a combustion product (e.g., gasoline vapor or liquidand air) which is ignited, heated or spontaneously combusts after havingbeen mixed together at the point of ignition, heating or combustionthrough the action of orifices 36 a and 36 b. Note that as employedherein, the term “gas” includes within its scope air. Ignited orspontaneously-combusted jets or streams of gas or liquid (working fluid)(providing force f₁) act on distal end 15 of non-piezoelectricresonating element 14 for a first predetermined period of time and at apressure sufficient, and at a distance sufficiently close, to cause thedesired amount of deflection of distal end 15 of resonating element 14,after which first predetermined period of time the supply of gas orliquid is terminated until the next cycle of providing force f₁ begins.The working fluid may be heated by at least one of convection, heattransfer, radiation, combustion, an exothermic chemical reaction and anuclear reaction. The working fluid may be changed from a liquid to agas. The working fluid may be confined, such that expansion is onlyallowed toward a distal end of the non-piezoelectric resonating element14. It is preferable to detect a phase of the oscillations of thenon-piezoelectric resonating element 14 with some device, such that thetiming of the ignition, heating or spontaneously combustion of theworking fluid may be adjusted. It is preferable to detect an amplitudeof the oscillations of the non-piezoelectric resonating device 14. It ispreferable that a device be chosen to adjust the amount of heat appliedto the working fluid based on the detected amplitude of the oscillationsof the non-piezoelectric resonating element 14. A duration of theignited, heated or spontaneously combusted working fluid does not exceedone half of a period of resonant oscillations of the non-piezoelectricresonating element 14. The working fluid is heated once for each cycleof oscillation of the non-piezoelectric resonating element 14. However,the working fluid may be applied to opposing sides of thenon-piezoelectric resonating element 14. As shown in FIG. 8, resonatingelement 14 deflects into first position a under the action of force f₁,force f₁ abates, resonating element 14 deflects into second position bunder the action of force f₂, and then oscillates and providesmechanical energy to piezoelectric element 12 through proximal end 17. Aportion of the mechanical energy transferred into piezoelectric element12 from resonating element 14 is converted into electrical energy bypiezoelectric element 12. After a second predetermined period of timehas passed since the termination of providing external force f₁, forcef₁ is provided again to deflect element 14 into first position a, andthe process repeats.

FIGS. 1 through 8 illustrate some fundamental concepts associated withthe various embodiments of the present invention. One such concept isthat externally-provided force f₁ may be supplied according to any of anumber of different methods and devices, including, but not limited to,resonating element 14 being excited by an external force or memberhaving or providing: (a) substantially the same principal resonantfrequency as element 14; (b) a principal resonant frequency lower thanthe principal resonating frequency of element 14; (c) a principalresonant frequency higher than the principal resonating frequency ofelement 14; (c) a series of single impacts; (d) contact pressure orforce; (e) a magnetic or electric field formed by permanent magnets, oneor more coils or a moving wire; (f) acceleration of a proof mass (g)pressure of a liquid, gas or steam; (h) pressure created by combustion;(i) force delivered generally through rotational motion; (j) forcedelivered generally through linear translational motion; (k) forceacting in a direction parallel to the direction of motion of resonatingelement 14; (l) force acting in a direction perpendicular to thedirection of motion of resonating element 14; (m) force acting in adirection that is neither parallel nor perpendicular to the direction ofmotion of resonating element 14; (n) force acting on a plurality ofresonating elements 14 sequentially or one at a time; and (0) forceacting on a plurality of resonating elements 14 simultaneously ornear-simultaneously.

Another fundamental concept illustrated or inferred by FIGS. 1 through 8is that resonating element 14 may assume any of a number of differentforms and embodiments, including, but not limited to: (a) a plurality ofresonating elements 14 each having a different principal resonantfrequency; and (b) a plurality of resonating elements 14 linked togetherto form a single resonating element 14.

FIG. 9 shows MEMS device 37 according to one embodiment of the presentinvention. MEMS device 37 comprises a piezoelectric element 12, siliconlayer 14 (which forms non-piezoelectric resonating element 14) andmagnetic layer 22. MEMS device 37 may be mounted on or otherwiseincorporated into a silicon substrate and used to generate electricityor periodic electrical signals, or may be configured to form a miniaturepiezoelectric motor or transformer. Reference is made to U.S. Pat. Nos.5,691,752; 6,013,970; 6,347,862; 6,911,107; 7,081,693 and 7,089,638listed hereinabove for further details concerning fabrication of MEMSdevices having piezoelectric layers or elements incorporated THEREIN.Silicon layer 14 may be fabricated using any of a number of deposition,photo-lithography, crystalline growth, micro-machining, etching, sol-geland other techniques and processes well known in the MEMS fabricationand thin-film manufacturing arts.

FIG. 10a shows one embodiment of an electricity generating system of thepresent invention. Externally-provided force f₁ is shown as beingsupplied by motor 40, which causes an output shaft to rotate and therebyprovide force f₁ to piezoelectric generator 10, which may assume any ofthe forms described above, or any combination or modification thereof.Note, however, that externally-provided force f₁ may be supplied by anyof a number of different devices or methods, including, but not limitedto, wind-powered devices, solar-powered devices, hand-cranks, internalcombustion engines, and so on. Alternating-current electricity generatedby piezoelectric generator 10 is supplied to circuit 42, which rectifiesac current into DC current in sub-circuit 44 and provides a DC outputacross the indicated output load terminals and battery or capacitor 46.

In another embodiment of the present invention, and as shown in FIG. 10b, circuit 42 is a multi-phase frequency rectifier circuit employing anLC filter, which is particularly useful in applications where multipleresonating elements 12 resonate at different frequencies. In yet anotherembodiment, and as shown in FIG. 10c , circuit 42 is a synchronousbipolar rectifier circuit employing power switching FETs instead ofdiodes. Upon having read and understood the specification, claims anddrawings hereof, those skilled in the art will understand that avirtually infinite number of suitable embodiments of circuits 42 may bedevised by one skilled in the art to convert the ac output provided bypiezoelectric generator 10 into a DC output voltage, that circuits 42shown in FIG. 11 illustrate but three such embodiments, and that suchcircuits 42 will fall within the scope of the present invention. Thoseskilled in the art will further understand that a virtually infinitenumber of different devices and applications may be driven by the outputvoltage provided by such circuits, such as battery charging circuits,charging batteries, providing DC current to one or more devices,powering DC devices, powering hybrid automobiles, and so on.

FIG. 11 shows one embodiment of transformer 50 of the present invention,where resonating element 14 is excited initially by an external voltageor current provided to piezoelectric element 12, where such voltage orfrequency has a frequency which substantially matches the principalresonant frequency of resonating element 14. In response to displacementinduced in piezoelectric element 12 a by the external current orvoltage, resonating element 14 oscillates in place and dissipatesmechanical energy into piezoelectric element 12 b, which is configuredto act as a load to resonating element 14. Electrical energy of the samefrequency as that provided to piezoelectric element 12 a is output bypiezoelectric element 12 b, but may have a different voltage dependingon the particular design parameters selected for the various componentsof transformer 50 illustrated in FIG. 12.

FIG. 12 shows one embodiment of a method of the present invention forgenerating electricity. In step 110, piezoelectric element 12 isoperably coupled to non-piezoelectric resonating element 14. In step115, moving element 16 is used to deflect resonating element 14 to firstposition a. In step 120, resonating element 14 is released from firstposition a and permitted in step 125 to deflect to position b.Resonating element 14 then oscillates between first position a andsecond position b in step 130. In step 135, at least a portion ofmechanical energy generated by the oscillation of resonating element 14is transferred to piezoelectric element 12. In step 140, electricity isgenerated by piezoelectric element 12 in response to the mechanicalenergy being provided thereto. Upon having read and understood thespecification, claims and drawings hereof, those skilled in the art willrealize that a virtually infinite number of variations and modificationsof the foregoing method may be devised by one skilled in the art, andthat such variations and modifications will fall within the scope of thepresent invention.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, therefore, that other expedientsknown to those skilled in the art or disclosed herein may be employedwithout departing from the invention or the scope of the appendedclaims. For example, the present invention is not limited to resonatingelements in piezoelectric machines or systems where one or moreresonating elements 14 deform or deflect in reaction to compressionalforces being applied thereto, but also where one or more resonatingelements 14 deform or deflect in reaction to shear or bending forcesbeing applied thereto, or to any combination of compressional, shear orbending forces being applied thereto. Piezoelectric element 12 of thepresent invention is not limited to embodiments having a single layer ofpiezoelectric material. Instead, piezoelectric element 12 may compriseany suitable number of layers of piezoelectric material laminated,glued, compressed or otherwise bound or held together. Piezoelectricelement 12 may be formed of any suitable piezoelectric material, theprocesses for making same being well known in the art. In addition, thepresent invention includes within its scope systems, devices, componentsand methods where one device serves as both a piezoelectric generatorand a piezoelectric motor. One application for such a device is in ahybrid automobile or other hybrid transportation device such as a hybridmotorcycle, hybrid bicycle or hybrid boat or vessel.

Note further that the present invention includes within its scope notonly piezoelectric generators, but also piezoelectric motors, whereinthe processes and steps described hereinabove are basically reversedsuch that: (a) externally-provided electrical current and voltage aresupplied to piezoelectric element 12; (b) element 12 is operably coupledto proximal end 17 of resonating element 14 and transfers mechanicalenergy thereto in response to piezoelectric element 12 deforming andgenerating displacement of portions thereof as electrical current andvoltage are supplied thereto; (c) resonating element 14 oscillates inresponse to mechanical energy being provided thereto by piezoelectricelement 12; (d) distal end 17 of resonating element deflects into firstposition a, and engages and causes translational movement or motion ofmoving element 16; (e) distal end 17 of resonating element deflects intosecond position b; (f) steps (a) through (e) are repeated. In thegeneral case where a piezoelectric motor of the present invention is tobe operated in accordance with the steps outlined above, however, someexternal force typically must be provided to set the stator orequivalent element in motion initially.

Piezoelectric element 12 may be attached to proximal end 17 using any ofa number of different means, including, but not limited to, clamps,frames or other structural members that compress, hold or secure aportion of piezoelectric element 12 therebetween, adhesives, epoxies,plastics, thermoplastics, fusing materials, fasteners, screws, nuts andbolts, rivets, and other means of affixing, fastening or otherwiseattaching or bonding proximal end 17 to piezoelectric element 12. Otherelements may also be disposed between proximal end 17 and piezoelectricelement 12, such as springs, gears, deformable members, plastic,thermoplastic, metal, and the like, depending on the particularrequirements and application at hand.

Having read and understood the present disclosure, those skilled in theart will now understand that many combinations, adaptations, variationsand permutations of known piezoelectric, electrical, electronic andmechanical systems, devices, components and methods may be employedsuccessfully in the present invention.

In the claims, means plus function clauses are intended to cover thestructures described herein as performing the recited function and theirequivalents. Means plus function clauses in the claims are not intendedto be limited to structural equivalents only, but are also intended toinclude structures which function equivalently in the environment of theclaimed combination.

All printed publications and patents referenced hereinabove are herebyincorporated by referenced herein, each in its respective entirety.

I claim:
 1. A method of generating electric power comprising the stepsof: providing a non-piezoelectric resonating element; attaching one sideof a piezoelectric element to a proximal end of said non-piezoelectricelement, attaching an opposing side of said piezoelectric element to abase; heating a working fluid in proximity to a distal end of saidnon-piezoelectric resonating element; directing repeatedly said heatedworking fluid to expand toward and apply pressure to a distal end ofsaid non-piezoelectric resonating element to cause a distal end of saidnon-piezoelectric resonating element to oscillate; deforming saidpiezoelectric element with repeated oscillations of said distal end ofsaid non-piezoelectric resonating element to create a deformedpiezoelectric element; transferring electrical current generated by saiddeformed piezoelectric element to the electrical load; and heating saidworking fluid to coincide with said distal end of said non-piezoelectricresonating element moving away from said expanding working fluid, aduration of said heating does not exceed one half of a period ofresonant oscillations of said non-piezoelectric resonating element. 2.The method of generating electric power of claim 1 further comprisingthe step of: providing at least one of convection, heat transfer,radiation, combustion, an exothermic chemical reaction and a nuclearreaction for heating said working fluid.
 3. The method of generatingelectric power of claim 1, further comprising the step of: changing astate of said working fluid from a liquid to a gas.
 4. The method ofgenerating electric power of claim 1, further comprising the step of:confining said working fluid such that expansion is only allowed towarda distal end of said non-piezoelectric resonating element.
 5. The methodof generating electric power of claim 1, further comprising the step of:detecting a phase of oscillations of said non-piezoelectric resonatingelement.
 6. The method of generating electric power of claim 5, furthercomprising the step of: providing a device for adjusting a timing ofsaid working fluid based on a detected phase of oscillations of saidnon-piezoelectric resonating element.
 7. The method of generatingelectric power of claim 1, further comprising the step of: providing adevice for detecting an amplitude of said oscillations of saidnon-piezoelectric resonating element.
 8. The method of generatingelectric power of claim 7, further comprising the step of: providing adevice to adjust an amount of heat applied to said working fluid basedon a detected amplitude of said oscillations of said non-piezoelectricresonating element.
 9. The method of generating electric power of claim1, further comprising the step of: heating said working fluid once foreach cycle of oscillations of said non-piezoelectric resonating element.10. The method of generating electric power of claim 1, furthercomprising the step of: applying said heated working fluid to opposingsides of said non-piezoelectric resonating element for each cycle ofoscillations.
 11. The method of generating electric power of claim 1,further comprising the step of: rectifying electrical current flowingfrom said piezo electric element.
 12. The method of generating electricpower of claim 11, further comprising the step of: directing saidrectified electrical current into one of a battery and an electricalenergy storage device.